It has been known hitherto that a rice-milling apparatus comprises a plurality of vertical abrasive rice-milling machines arranged in a row, a plurality of horizontal friction rice-milling machines arranged in a row, and any suitable number of polishing machines, the brown rice being milled through the rice-milling process by changing over channels between the rice-milling machines (refer to Patent Reference 1).
With this arrangement, an operator decides which rice-milling machine should be used and how many times brown rice should be passed through the rice-milling machines depending upon variety and quality of the rice, in order to finish the rice at the desired milling yield, embryo-stripping rate, and rice-milling degree.
It has also been known that a rice-milling apparatus includes an abrasive rice-milling process conducted in an abrasive rice-milling machine, which is followed by a friction rice-milling process conducted in a friction rice-milling machine, these rice-milling processes being arranged in series. In this rice-milling apparatus, there is provided a brown rice feed channel for feeding brown rice directly to the friction rice-milling process without going through the abrasive rice-milling process, by means of a channel change-over means (refer to Patent Reference 2).
Tests of characteristics of brown rice to be fed to the rice-milling apparatus have previously been carried out, and soft brown rice having good embryo-elimination is first fed to the abrasive rice-milling process to cut the waxy portion of the brown rice epidermis, thereby increasing the friction coefficient of the rice surface, and the bran layer is then removed from the rice grain in the friction rice-milling process under relatively low pressure for the rice milling. On the other hand, brown rice having bad embryo elimination is fed through the feed channel directly to the friction rice-milling process by the channel change-over means, and relatively high pressure is exerted on the rice grains in the friction rice-milling process to eliminate the entire embryo together with the tough embryo epidermis. In short, both rice grains having easy-to-remove embryos and rice grains having difficult-to-remove embryos can be milled to a high milling yield and high quality.
In those rice-milling apparatuses as disclosed in Patent References 1 and 2, however, because the means for changing over the channels between the rice-milling machines includes a large-sized bucket elevator and a channel change-over device located at the upper portion of the bucket elevator, work is required to remove rice grains which might be accumulated within the lower portion of the bucket elevator and the channel change-over device, prior to lot-changing. As a result, there is a problem with taking time to change a lot. In the conventional rice-milling apparatus, the plural rice-milling machines lead to a long rice-milling process, an increase in rice milling time, and poor economy, such as an increase in electricity costs. In the recent rice-milling field, it has been desired to provide energy-saving types of facilities, where a smaller lot size and a shorter flow lead to a reduction in the number of rice-milling processes, shortening of rice-milling time, and reduction in electricity costs.